Simulate loop analysis for goto-label pairs

src/Analyser/NodeScopeResolver.php

@@ -38,6 +38,7 @@
 use PhpParser\Node\Stmt\Echo_;
 use PhpParser\Node\Stmt\For_;
 use PhpParser\Node\Stmt\Foreach_;
+use PhpParser\Node\Stmt\Goto_;
 use PhpParser\Node\Stmt\If_;
 use PhpParser\Node\Stmt\InlineHTML;
 use PhpParser\Node\Stmt\Return_;
@@ -110,6 +111,7 @@
 use PHPStan\Node\VarTagChangedExpressionTypeNode;
 use PHPStan\Parser\ArrowFunctionArgVisitor;
 use PHPStan\Parser\ClosureArgVisitor;
+use PHPStan\Parser\GotoLabelVisitor;
 use PHPStan\Parser\ImmediatelyInvokedClosureVisitor;
 use PHPStan\Parser\LineAttributesVisitor;
 use PHPStan\Parser\Parser;
@@ -408,12 +410,59 @@ private function processStmtNodesInternalWithoutFlushingPendingFibers(
 			|| $parentNode instanceof Node\Stmt\ClassMethod
 			|| $parentNode instanceof PropertyHookStatementNode
 			|| $parentNode instanceof Expr\Closure;
+
 		foreach ($stmts as $i => $stmt) {
-			if ($alreadyTerminated && !($stmt instanceof Node\Stmt\Function_ || $stmt instanceof Node\Stmt\ClassLike)) {
+			if ($alreadyTerminated && !($stmt instanceof Node\Stmt\Function_ || $stmt instanceof Node\Stmt\ClassLike || $stmt instanceof Node\Stmt\Label)) {
 				continue;
 			}
 
 			$isLast = $i === $stmtCount - 1;
+
+			$nestedLabelNames = $stmt->getAttribute(GotoLabelVisitor::NESTED_BACKWARD_GOTO_LABELS_ATTRIBUTE);
+			if ($nestedLabelNames !== null && $context->isTopLevel()) {
+				$originalStorage = $storage;
+				$bodyScope = $scope;
+				$count = 0;
+				do {
+					$prevScope = $bodyScope;
+					$tempStorage = $originalStorage->duplicate();
+					$bodyScopeResult = $this->processStmtNodesInternal(
+						$parentNode,
+						[$stmt],
+						$bodyScope,
+						$tempStorage,
+						new NoopNodeCallback(),
+						$context->enterDeep(),
+					);
+
+					$gotoScope = null;
+					foreach ($bodyScopeResult->getExitPoints() as $ep) {
+						$epStmt = $ep->getStatement();
+						if (!($epStmt instanceof Goto_) || !isset($nestedLabelNames[$epStmt->name->toString()])) {
+							continue;
+						}
+
+						$gotoScope = $gotoScope === null ? $ep->getScope() : $gotoScope->mergeWith($ep->getScope());
+					}
+
+					if ($gotoScope !== null) {
+						$bodyScope = $scope->mergeWith($gotoScope);
+					}
+
+					if ($bodyScope->equals($prevScope)) {
+						break;
+					}
+
+					if ($count >= self::GENERALIZE_AFTER_ITERATION) {
+						$bodyScope = $prevScope->generalizeWith($bodyScope);
+					}
+					$count++;
+				} while ($count < self::LOOP_SCOPE_ITERATIONS);
+
+				$scope = $bodyScope;
+				$storage = $originalStorage;
+			}
+
 			$statementResult = $this->processStmtNode(
 				$stmt,
 				$scope,
@@ -424,6 +473,76 @@ private function processStmtNodesInternalWithoutFlushingPendingFibers(
 			$scope = $statementResult->getScope();
 			$hasYield = $hasYield || $statementResult->hasYield();
 
+			if ($stmt instanceof Node\Stmt\Label) {
+				$labelName = $stmt->name->toString();
+
+				$newExitPoints = [];
+				foreach ($exitPoints as $exitPoint) {
+					$exitStmt = $exitPoint->getStatement();
+					if ($exitStmt instanceof Goto_ && $exitStmt->name->toString() === $labelName) {
+						if ($alreadyTerminated) {
+							$scope = $exitPoint->getScope();
+							$alreadyTerminated = false;
+						} else {
+							$scope = $scope->mergeWith($exitPoint->getScope());
+						}
+					} else {
+						$newExitPoints[] = $exitPoint;
+					}
+				}
+				$exitPoints = $newExitPoints;
+
+				if ($alreadyTerminated) {
+					continue;
+				}
+
+				if ($stmt->getAttribute(GotoLabelVisitor::HAS_BACKWARD_GOTO_ATTRIBUTE) === true && $context->isTopLevel()) {
+					$originalStorage = $storage;
+					$bodyStmts = array_slice($stmts, $i + 1);
+					$bodyScope = $scope;
+					$count = 0;
+					do {
+						$prevScope = $bodyScope;
+						$bodyScope = $bodyScope->mergeWith($scope);
+						$tempStorage = $originalStorage->duplicate();
+						$bodyScopeResult = $this->processStmtNodesInternal(
+							$parentNode,
+							$bodyStmts,
+							$bodyScope,
+							$tempStorage,
+							new NoopNodeCallback(),
+							$context->enterDeep(),
+						);
+
+						$gotoScope = null;
+						foreach ($bodyScopeResult->getExitPoints() as $ep) {
+							$epStmt = $ep->getStatement();
+							if (!($epStmt instanceof Goto_) || $epStmt->name->toString() !== $labelName) {
+								continue;
+							}
+
+							$gotoScope = $gotoScope === null ? $ep->getScope() : $gotoScope->mergeWith($ep->getScope());
+						}
+
+						if ($gotoScope !== null) {
+							$bodyScope = $scope->mergeWith($gotoScope);
+						}
+
+						if ($bodyScope->equals($prevScope)) {
+							break;
+						}
+
+						if ($count >= self::GENERALIZE_AFTER_ITERATION) {
+							$bodyScope = $prevScope->generalizeWith($bodyScope);
+						}
+						$count++;
+					} while ($count < self::LOOP_SCOPE_ITERATIONS);
+
+					$scope = $bodyScope;
+					$storage = $originalStorage;
+				}
+			}
+
 			if ($shouldCheckLastStatement && $isLast) {
 				$endStatements = $statementResult->getEndStatements();
 				if (count($endStatements) > 0) {
@@ -917,6 +1036,18 @@ public function processStmtNode(
 			return new InternalStatementResult($scope, $hasYield, true, [
 				new InternalStatementExitPoint($stmt, $scope),
 			], $overridingThrowPoints ?? $throwPoints, $impurePoints);
+		} elseif ($stmt instanceof Goto_) {
+			$hasYield = false;
+			$throwPoints = [];
+			$impurePoints = [];
+
+			return new InternalStatementResult($scope, $hasYield, true, [
+				new InternalStatementExitPoint($stmt, $scope),
+			], $overridingThrowPoints ?? $throwPoints, $impurePoints);
+		} elseif ($stmt instanceof Node\Stmt\Label) {
+			$hasYield = false;
+			$throwPoints = $overridingThrowPoints ?? [];
+			$impurePoints = [];
 		} elseif ($stmt instanceof Node\Stmt\Expression) {
 			if ($stmt->expr instanceof Expr\Throw_) {
 				$scope = $stmtScope;
@@ -4800,6 +4931,9 @@ private function getNextUnreachableStatements(array $nodes, bool $earlyBinding):
 		$stmts = [];
 		$isPassedUnreachableStatement = false;
 		foreach ($nodes as $node) {
+			if ($node instanceof Node\Stmt\Label) {
+				break;
+			}
 			if ($earlyBinding && ($node instanceof Node\Stmt\Function_ || $node instanceof Node\Stmt\ClassLike || $node instanceof Node\Stmt\HaltCompiler)) {
 				continue;
 			}

src/Parser/GotoLabelVisitor.php

@@ -0,0 +1,177 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Parser;
+
+use Override;
+use PhpParser\Node;
+use PhpParser\Node\Stmt\Goto_;
+use PhpParser\NodeVisitorAbstract;
+use PHPStan\DependencyInjection\AutowiredService;
+use function array_slice;
+use function is_array;
+
+#[AutowiredService]
+final class GotoLabelVisitor extends NodeVisitorAbstract
+{
+
+	public const HAS_BACKWARD_GOTO_ATTRIBUTE = 'hasBackwardGoto';
+
+	public const NESTED_BACKWARD_GOTO_LABELS_ATTRIBUTE = 'nestedBackwardGotoLabels';
+
+	#[Override]
+	public function beforeTraverse(array $nodes): ?array
+	{
+		$this->processStatementList($nodes);
+		return null;
+	}
+
+	#[Override]
+	public function enterNode(Node $node): ?Node
+	{
+		if ($node instanceof Node\PropertyHook) {
+			if (is_array($node->body)) {
+				$this->processStatementList($node->body);
+			}
+			return null;
+		}
+
+		if (
+			$node instanceof Node\Stmt\Function_
+			|| $node instanceof Node\Stmt\ClassMethod
+			|| $node instanceof Node\Expr\Closure
+			|| $node instanceof Node\Stmt\If_
+			|| $node instanceof Node\Stmt\ElseIf_
+			|| $node instanceof Node\Stmt\Else_
+			|| $node instanceof Node\Stmt\Case_
+			|| $node instanceof Node\Stmt\Catch_
+			|| $node instanceof Node\Stmt\Do_
+			|| $node instanceof Node\Stmt\Finally_
+			|| $node instanceof Node\Stmt\For_
+			|| $node instanceof Node\Stmt\Foreach_
+			|| $node instanceof Node\Stmt\Namespace_
+			|| $node instanceof Node\Stmt\TryCatch
+			|| $node instanceof Node\Stmt\While_
+			|| $node instanceof Node\Stmt\Block
+			|| $node instanceof Node\Stmt\Declare_
+		) {
+			$stmts = $node->stmts ?? [];
+			if ($stmts !== []) {
+				$this->processStatementList($stmts);
+			}
+		}
+
+		return null;
+	}
+
+	/**
+	 * @param array<Node> $stmts
+	 */
+	private function processStatementList(array $stmts): void
+	{
+		$labelIndices = [];
+		foreach ($stmts as $idx => $s) {
+			if (!($s instanceof Node\Stmt\Label)) {
+				continue;
+			}
+
+			$labelIndices[$s->name->toString()] = $idx;
+		}
+
+		if ($labelIndices !== []) {
+			foreach ($labelIndices as $labelName => $labelIdx) {
+				$stmtsAfterLabel = array_slice($stmts, $labelIdx + 1);
+				if ($stmtsAfterLabel === []) {
+					continue;
+				}
+				/** @var Goto_[] $gotos */
+				$gotos = $this->findWithinScope($stmtsAfterLabel, Goto_::class);
+				foreach ($gotos as $goto) {
+					if ($goto->name->toString() === $labelName) {
+						$stmts[$labelIdx]->setAttribute(self::HAS_BACKWARD_GOTO_ATTRIBUTE, true);
+						break;
+					}
+				}
+			}
+		}
+
+		foreach ($stmts as $s) {
+			if ($s instanceof Node\Stmt\Label) {
+				continue;
+			}
+			/** @var Node\Stmt\Label[] $nestedLabels */
+			$nestedLabels = $this->findWithinScope([$s], Node\Stmt\Label::class);
+			if ($nestedLabels === []) {
+				continue;
+			}
+			/** @var Goto_[] $nestedGotos */
+			$nestedGotos = $this->findWithinScope([$s], Goto_::class);
+			if ($nestedGotos === []) {
+				continue;
+			}
+			$nestedLabelNames = [];
+			foreach ($nestedLabels as $nestedLabel) {
+				$nestedLabelNames[$nestedLabel->name->toString()] = true;
+			}
+			$matchedLabels = [];
+			foreach ($nestedGotos as $nestedGoto) {
+				$gotoName = $nestedGoto->name->toString();
+				if (!isset($nestedLabelNames[$gotoName])) {
+					continue;
+				}
+				$matchedLabels[$gotoName] = true;
+			}
+			if ($matchedLabels === []) {
+				continue;
+			}
+
+			$s->setAttribute(self::NESTED_BACKWARD_GOTO_LABELS_ATTRIBUTE, $matchedLabels);
+		}
+	}
+
+	/**
+	 * @param array<mixed> $nodes
+	 * @param class-string<Node> $class
+	 * @return Node[]
+	 */
+	private function findWithinScope(array $nodes, string $class): array
+	{
+		$results = [];
+		$this->collectWithinScope($nodes, $class, $results);
+		return $results;
+	}
+
+	/**
+	 * @param array<mixed> $nodes
+	 * @param class-string<Node> $class
+	 * @param Node[] $results
+	 */
+	private function collectWithinScope(array $nodes, string $class, array &$results): void
+	{
+		foreach ($nodes as $node) {
+			if (!$node instanceof Node) {
+				continue;
+			}
+			if ($node instanceof $class) {
+				$results[] = $node;
+			}
+			if (
+				$node instanceof Node\Stmt\Function_
+				|| $node instanceof Node\Stmt\ClassMethod
+				|| $node instanceof Node\Expr\Closure
+				|| $node instanceof Node\Stmt\ClassLike
+				|| $node instanceof Node\PropertyHook
+			) {
+				continue;
+			}
+			foreach ($node->getSubNodeNames() as $name) {
+				$sub = $node->{$name};
+				if ($sub instanceof Node) {
+					$this->collectWithinScope([$sub], $class, $results);
+				} elseif (is_array($sub)) {
+					$this->collectWithinScope($sub, $class, $results);
+				}
+			}
+		}
+	}
+
+}

tests/PHPStan/Analyser/nsrt/bug-4674.php

@@ -0,0 +1,34 @@
+<?php declare(strict_types = 1);
+
+namespace Bug4674;
+
+use function PHPStan\Testing\assertType;
+
+/**
+ * @return string|false
+ */
+function string_or_false()
+{
+	if (rand(1,2)==1)
+		return "string";
+	return false;
+}
+
+function takes_string(string $s): void
+{
+	echo $s;
+}
+
+function test(): void
+{
+	$a = string_or_false();
+	if ($a === false)
+		goto end;
+
+	assertType('string', $a);
+	takes_string($a);
+
+	end:
+	assertType('string|false', $a);
+	echo "finished";
+}